1. Field of the Invention
The present invention relates to an exhaust gas purification system for an internal combustion engine.
2. Description of the Prior Art
Exhaust gas purification systems are known each of which comprises either simply a secondary air supply system or an exhaust gas recirculation system, or both of them. Many of the known exhaust gas purification systems are arranged such that the speed of the engine operation is electrically detected to emit an electric signal to a solenoid valve or valves for the control of the rate of the secondary air supply and/or the rate of exhaust gas recirculation in relation to the engine speed. The known exhaust gas purification systems of this type, however, fail to provide a satisfactory volumetrically proportional control.